Production of hydrocarbons



` Feb. 26, 194%6. J, ANDERSON. ETAL 2,395,775/

K PRODUCTON oF HYDRocARBoNs 'Filed Feb. 22, 1945 leobuane invzniors: John Andzrson Robar? C. Casnzr named Feb. ze, 194s vPRODUCTION or HYDROCARBONS Jolm Anderson and Robert C. astner, Berkeley,

Calif., assignors to Shell Development Company, San Francisco. Calif., a corporation of Delaware Application February 22, 1943, Serial No. 476,714

7 Claims.

This invention relates to the treatment of oleilnic mixtures to produce higher boiling hydrodifferent olens of olenic mixtures without having to resort to expensive preliminary fractionation of such mixtures. Still another object is to reduce the amount of reagents, particularly acid reagents, required for producing alkylation products. One specific embodiment of the invention has as a special object the production of isoparamnic and aromatic hydrocarbon mixtures which are superior blending agents for aviation gasoline, particularly as regards power output of thev gasoline under conditions of rich mixture operation. Still other objects and advantages of the invention will be apparent from the following detailed description of the new method of operation.

For the purpose of making the invention clear it will be described with more particular reference to its application to the treatment of butane-butylene fractions of petroleumv cracking ments that this separation is eiliolently and economically effected by means of a reagent used in another step of the process and therefore without adding to the cost of operation. Thus, forthe production of the highest yield of alkylation products of high power output, the isobutylene content of the starting fraction is used with vbenzene to produce tertiary butyl'benzene while the secondary butylenes are reacted with isobutane toproduce branched chainoctanes, and sulfuric acid from the benzene treatment step is employed for separation o'f the butylenes prior to these reactions. For the purpose of illustrating the combination of steps characteristic of this procedure, the attached drawing shows, diagrammatically, a typical process ow. Referring to the drawing, isobutane from any suitable. source, for example, fractionation of products. However, this application of the process is intended to be illustrative only and it will be understood that the invention is not limitedwith respect to either the nature or source of the olens employed as starting materials.

Butane-butylene fractions are being used on a large scale for the production of blending agents for aviation motor fuels. These fractions are most widely used for alkylating isobutane inthe presence of concentrated sulfuric acid as this procedure is more emcient and economical than any of the other available methods of producing high octane number motor fuels from such starting materials. It has been found, however, that not only can the quality of the product so obtained be further improved, but also the consumption of sulfuric acid in the process can be reduced, thus making the procedure even more economical. These advantages are obtained by carrying out the reaction of the Yisobutylene present in the starting material under conditions different from those used for conversion of the less reactive alpha and beta butylenes present therewith. The partial separation of these olens by conventionalfractionation methods is possible but quite expensive, while separation of isobutylene from alpha butylene in this manner is entirely impractical because of the small dierences between their boiling points, and it is a feature of the invention in one of its preferred embodinatural gases or isomerization of normal butane,

advantageously the normal butane recoveredy from a later stage of the present process as hereinafter described, is introduced through line I to the rst alkylationunit 2. This alkylation unit is' preferably-of the type described invUnited States Patent 2,232,674 comprising a closed oircuit through which an emulsion of lhydrocarbon and concentrated sulfuric acid under alkylating conditions is pumped. Secondary butylenes for reaction with the isobutane are fed to the first alkylationV unitby line 3 and the sulfuric acid necessary to maintain the concentration of the acid in the circulating emulsion at an'effective value, preferably above is supplied by line The products of reaction are withdrawn by A line 5 to a separating zone 6 which may comprise settling, hydrocarbon neutralization and fractional distillation equipment in which the reacted emulsion is separated into an acid phase and a hydrocarbon phase; the latter is scrubbed with caustic and fractionated into an isobutane fraction which, in case it contains substantial amounts of lighter gases, may be subjected to stripping for their removal, a normal butane fraction, anda higher boiling fraction of parafiinic alkylation products which it may be desirable to further fractionate to separate a small amount of heavy ends which are undesirable in aviation gasoline. The isobutane fraction is returned to the alkylation unit by lines 'l and 3 tosupply the desired large excess of isobutane to olefin in the reaction, preferably at least 5 mols of isobutane per mol of olefin in the feed. The normal butane fraction is removed by line 8 and may be conducted to an isomerization unit, not shown, for conversion to isobutane for use in the process as previously indicated or may be dehydrogenated to form o lens useful as feed to the nrstalkylation unit or for the of butadiene or other The parafiinic alkylation products mures. whichwillbesubstantiallybranchedchainpar aiiins of eight carbon atoms .per molecule are removed by line l and used for blending with other products of the process as hereinafter described..

The withdrawn acid phase is separated into two parts, the maior portion being returned to the first alkylation unit by line I0, while the remainder, an amount corresponding approximately to the fresh acid of higher concentration introduced by line il at a temperature of aboutv C. to 50 C. for a period of about 5 to 15 minutes, preferably using about 0.1 to 0.25 volume of n acid per volume of benzene. By this treatment undesirable components of the benzene, particularly sulfur-containing compounds such as thiophene, are removed and the final quality of the of such products per volume of starting acid are materially improved. The reacted emulsion is removed by line i8 to'a separator i1 which is preferably a decantation vessel or the like wherein the treated benzene is separated and removed by line i8 and the acid is withdrawn byline I8. A part oi' the acid is returned to treater il by line 20 and the remainder, usually corresponding to about 20 to 50'; pounds per barrel of benzene treated, is conducted to a dilution tank 2i which may also receiveacid from line 22, as will be more fullyexplained hereinafter. In tank 2l the acid containing the absorbed iscbutylene, is fed-by line u toa polymerization unit I5 in which it is brought to a temperature of about 70 C. to 110- -C. in order to convert the isobutylene to polymers,

mainly di-isobutylene. The 'polymerization of the absorbed olefin may advantageously be carmixture may be withdrawn kfrom polymerizer 3S' by line 81 and fed to a separation unit 38 comprising the settling tanks.' and hydrocarbon neutralizlng and fractionating equipment suitable for separating the mixture into an acid phase and hydrocarbon streams comprising polymer of the desired boiling range for reaction with the previously mentioned 'pretreated benzene and lower andhigher boiling hydrocarbons. The acid phase is removed by line 88 and for the most part returned by line l0 for further use in absorption and polymerization of the isobutylene while the rev mainder'is removed from the system by line 4i. alkylation products of the process and the yield Line 42 represents-an outlet for n-butane and/cr is diluted with sufllcient water introduced by line 28 to reduce the concentration of the sulfuric acid to about 60% to '70%. The diluted acid is passed byline to separator-28 where they impurities liberated by the dilution are permitted to .accumulate asan upper layer which may be drawn oil! by line 21. lMost preferably, the acid is cooled during dilution to maintain a temperature lnot greater than that employed in the benzene treatment step as this facilitates separation of impurities from the acid and reduces undesirable side reactions. The separationof the impurities may be further facilitated by intimately mixing the acid either in tank 2| or more preferably in separator 26 with a solvent for the impurities, advantageously liquefied normal butane from line l introduced by line 24. Evaporation of a part of such butane provides an emcient method of maintaining the acid at the desired low temperature. The diluted and at leastparti'ally puried acid is conducted by line 28 to an olefin absorption unit 20 which may advantageously be an apparatus of the type described in United States Patent 1,955,- 873, or of the type claimed in United States Patent 2,022,205, or of other suitable form. In the absorption unit the acid contacts a butane-butyl- A ene fraction containing' isobutylene, normal buwith only relatively small absorption of normal other undesired components oi the hydrocarbon phase. The polymer produced is transferred by line Il to the second alkylation unit of the system 4I which may be of the same type as, or different from, the rst alkylation unit 2.

, In the second alkylation unit contacted with pretreated benzene' from separator i'l, preferably caustic and water washed in units not shown, introduced by line I8. As catalyst for the reaction of the polymer with the benzene, sulfuric acid from line l2 is used. This acid is preferably diluted in tank I4 with water introduced by line 46 in an amount sumcient to reduce the acid concentration to between and preferably about 85% and 88%, on a hydrocarbon-free basis. The diluted catalyst acid which may be stratied, extracted or otherwise treated to remove any impurities liberated by the dilutionis admitted to the second alkylation unit by line 41. Most advantageously, the alkylation of the benzene by the polymer is carried out -with a substantial molecular excess of benzene based upon the monomeric olefin equivalent of the polymer used, preferably at least four mols of benzene per mol of monomeric olen in the polymer. When using di-isobutylene, for example, most preferably six to ten mois of benzene are used per mol of polymer while nine to fifteen mols are preferably used per mol of' tri-isobutylene.

The reaction temperature under these conditions is maintained between about 40 C. and 50 C.,

butyl benzene may be obtained at 'atmospheric pressure but higher or lowerpressure may be used if desired.

The reacted emulsion from the second alkylation unit is conducted by line 48 to separation zone I9 wherein the mixture is separated into an acid phase and a hydrocarbon phase and the oleilns. The resulting mixture may be conducted 10 latter is fractionated, preferably after treatment to separator 32 by line Il and the unabsorbed hydrocarbon containing the normal butylenes may be removed by line 38 and conducted to the first aikylation zone by line 8 for reaction with at above C. with a base, advantageously with about 10% to 50% by volume of a caustic soda solution ofA 2% to 10% concentration at about C. to 160 C. for about 10 to 30 minutes isobutane, K as previously described. .The acid, 7l under superatmospheric pressure suiiicient to M the polymer is maintain the majority of the product in the liquid phase. The separated acid is withdrawn by line 50 and for themost part returned byline 5i to the alwlation unit. The remainder of the acid. approximately equivalent in amount to that introduced by line 41, is fed by line 22 to tank 2l as previously indicated. The separated excess benzene is removed by line 52 and a part is returned to the alkyiation unit by lines El and 43 while the remainder is conducted by lines 53 and it to acid treater i3 to prevent the accumulation in the system of undesirable components. The aromatic alkylatlon products. together, if desired,

with hydrocarbon diluents and/or a part of the excess unreacted benzene which may, if necessary, be later separated. are withdrawn by line 5d and fed, along with the pac alwlation products from line 0, by line 58 to storage, reg resented by unit El.

The following specific example illustrates the improved'results, particularly with respect to in.

creased yield of higher value aviation motor fuel.

obtainable by the process described in this invention. These results are based upon a. chargins stock ci' Dubbs cracking products having the folio composition:

Per cent Propane l Isobutylene 18 Normal butylenes 29 Isobutane' 12 Normal butane 40A The operating conditions for the 'dierent stages of treatment are as follows:

Isobutylene absorption in diluted isobutane alkylation acid fom benzene treatment HaSOr concentration in diluted acid assuma.

' giving a polymer containing 74.0%

90%.01 the isobutyiene' and .less than 5%.'oi the secondary butylen'es are removed in the absorption step. The residual oleilrlic hydrocarbon feed to -the isobutane alkylation has the following composition:

Per cent Propane 1.2 Isobutylene 2.2 Normal butylene 331.6 Isobutane 14.5 Normal butane- 43.6

m the-.polymerization step 98.8% brule' at:l

sor-bed isobutylene was removed from the acid of di-iaoilation unit.

butylene as feed to the benzene v= The benzene pretreatment' using be containing 0.47%l sulfur as feed resulted in 'a reducper cent-- Acid to hydrocarbon ratio 0.1 to l Temperature -..C-... 20 Average time of contact-.. minutes 5 Polymerization of absorbed isobutylene Average temperature "C... 89 Residence time in time tank ..minutes 6 Mols isobutylene per mol HzSO4; 1.18

Mols added butane per mol isobutylene 1.24

Benzene pretreatment with isobutane valleviation acid tion of the sulfur content to 0.06%.'lation of this benzene with the di-iaobutylene gave an alkylation product conta "24.3% of tertiary butyl benzene,y the remainder Vbeing mostly di-tertiary butyl benzene which may be recycled to v the alkylation along with the excess benzene and unreacted di-isobutylene to obtain substantially quantitative production of the desired monotertiary butyl benzene or a yield of 233% by weight based on the isobutylene used. 'Recycling of the di-tertiary butyl benzene may, however, be omitted and this product separately recovered. From the alkylation of isobutane with the residual butylenes from the polymerization, a. yield of alkylation products oi 201% was obtained. These yields correspond to a totalproduction of allnvlation products equal to 175% by volume based on the oleiins fed. When blended, in equal volumes. with 50% oi an aviation basestock oi'73 O. N. and tested,'the allowable power output at rich mixtures of these alkylatlon products containing 3 cc. ot lead tetraethyl is 1.33 times that of a corresponding blend what would be obtained if the oleiins were used exclusively for alkylation of isobutane. I

The increased yield and quality of the alkylaltion products are obtained without any increase in sulfuric acid consumption since the acid from the isoparailln alkylation is used in the other acid-consuming steps of the process. In view of the detrimentaleiect which organic impurities picked up during alkylation of isoparailinswith olefins have on the catalytic activity of sulfuric acid, it is surprising that the isoparamn alkylati'on acid can thus be emciently used for subsequent alkylations of aromatic hydrocarbons. It also could not have been predicted that such acid could be used for pretreatment of the benzene to be alkylated. This latter procedure is of advantage evenfwhen using different catav lysts for the two alkylation operations. Thus,

- a phosphoric acid catalyst.

Titratable acidity of treating acid (as H2804) -..per cent-.. 92 Total volumes of acid per volume of benzene 0.25 to 1 Temperature -..C 35 Average `time of treatment minutes 10 Alkylation 0i d! isobltl'ilme W naar este with bufwn" ro mlyme.' polymerization Concentration of sulfuric acid- Fed to reactor percent'.. 80 98 Withdrawn from reactor .do.- 70 92 Acid to hydrocarbon volume ratio in reactor 0.25 to l 1 to i Average contact time inreactor mnutes.. m Average temperature-. -.C-. 20 Mols oi benzene per mol of polymerinfeed. 9.8 to l Mols of isobutane per moloioleiin inieed-. l5 to l Under these operating conditions approximately sulfuric acid from the isoparafiln alkylation step may be used iirst to treat benzene and then for the preparation of the polymers and the latter then reacted with benzene in the presence of As an example of such operations, polymers identical with those described in the foregoing speci-tlc example were reacted with benzene which had been pretreated,

Pressure Mol ratio benzene to po ymer Tertiary butyl benzene Imation.

as described, in the presence of a solid phosphoric. acid catalyst consisting of a calcined mixture of phosphoric acid and an absorbent clay. 'lhe operating conditions were as follows:

Run number Temperature C.-

l Feed rate (grs. per liter o! catalyst par hou...

The productsobtained had the following composition, expressed as mol percent of the total recovered hydrocarbon:

Fraction boiling below 75 0.... Di-isobutylene fraction Di-tertiary butyl benzene fraction..

dicated for the specific case employing sulfuricA acid catalysts, such acid beingA supplemented, ifv necessary, with acid from another source. v

Many other variations in the process may also b e made; thus, instead of selectively absorbing the isobutylene in the isoparaiiln alkylation acid prior to polymerization of the absorbed olefin, the polymerization may be carried out, either selectively or as a co-polymerization of the isobutylene with secondary butylenes or other olens, in one step by contacting the olefin-containing hydrocarbon with such acid under polymerizing conditions as described, for example,' in United States Patents 2,007,160 and 2,174,247. Alternatively, the polymerization step may be omitted entirely and preferably, using acid having the same concentration as that used for the second alkylation. the olefin may be absorbed in the acid as previously described and the absorpf vantageous method or operation is to allsylate` when propylene is used alone in the second alkylation step of the process for, although it il not practicable to carry out isoparaflln alkylatlons with propylene in the presence of sulfuric acid which has been employed for the alkylation of an isoparailln with other olens. such acid is quite suitable for the alkylation of aromatic hy drocarbons with propylene. An especially adisobutane in the first alkylation stage with one or more butylenes which may. if desired, be admixed with propylene, and then carry out the alkylation of the aromatic hydrocarbon with propylene in the presence of catalyst from the isobutane alkylation. Particularly when the allwlation of vthe aromatic hydrocarbon is carried out with an olen or oleiins directly,

' that is, without previous absorption and/cr polytion product from line 3l connected directly to unit 44 for alkylation of the benzene. Tertiary butyl benzene, for example, may be thus produced in very good yield. It is sometimes advantageous to add other oleilns during the second alkylation step, Thus, propylene may be added along vwith the isobutylene polymers and/or absorption products, and it has been found that the mixtures of cumene and, tertiary butylbenzene are fully equal to the products from alkylating benzene with isobutylene as far as their blending value in aviation gasoline is concerned. Furthermore, their vapor pressure is such that larger amounts can be successfully' included in the final gasoline without exceeding current distillation specincations. In fact, the

merizatlon treatment, it is advantageous to employ the residual unreacted olens, after fractionation to separate alkylation products. and normal parailins or other undesired components if necessary, as feed for the isoparaln alkylation step of the process. This method of operation is especially useful when the alkylation of aromatic hydrocarbons in unit M is leffected in the vapor phase with oleiins having four or more carbon atoms per molecule, while liquid phase alkylation methods are used for the isoparafiin alkylation in unit 2. It will be understood that, where isobutane alkylation has been referred to in the foregoing as being eiiected in a single unit represented in the drawing by unit 2, such alkylation may comprise a plurality of reaction stages in which the isobutane or other isoparamn or isoparailins are alkylated with the same or different oleiins using fresh catalyst for each of the alkylations, or more preferably adding such catalyst to one or more such stages only and carrying out the other isoparaftln alkylation stage or stages with catalyst which has been employed in the earlier alkylations. Thus. for example, when using sulfuric acid as the catalyst, isobutane may be alkylated with a butylene or with a butylene-propylene mixture while maintaining the desired catalyst concentration by adding fresh acid, and in another stage isobutane may be alkylated by reaction with amylenes in the presence of acid withdrawn from the butylene alkylation reaction. It will also be understood that in these alkylation stages r in any of the other operations of the process it maybe desirable to supplement or even in some cases to replace the acid or other catalyst from the preceding units with fresh catalyst in the later' reactions. The isobutane may alternatively be alkylated with polymer obtained by treatment of an olen-containing hydrocarbon mixture with theused liquid inorganic acid catalyst from alkylation of benzene with an olen as previously described.'

Not only may the process be carried out with other olens than those of three to ve carbon atoms or polymers thereof previously described by way of example but also either or both of the ters, either of organic or inorganic acids, as propyl, butyl 'or amyl, or higher alkyl sulfatos.

phosphates, borates, chlorides, formatos, acetates and the like, or ethers or alcohols may be used.

process of the invention offers many advantages Instead or isobutane, isopentane, isohexaue, 2,3-

' obtained.

dimethyl butane and other isoparaiiins having a tertiary carbon atom may be employed in the Ymatic hydrocarbons may be used in place of or along with benzene in the process, although when the aromatic alkylation product is intended for use in motor fuels volatility considerations make it advantageous to use lower boiling aromatic hydrocarbons, particularly benzene or toluene. It will thus be seen that the invention is applicable to the treatment of a wide variety of starting materials and is not limited to the details of operation and reaction conditions described by way of example, nor by any theory suggested in explanation of the improved results which are We claim as our invention: y

l. A process for producing motor fuel components of high anti-knock value which comprises reacting isobutane with a normal butylene in the presence of concentrated sulfuric acid, separatingthe resulting alkylation products from Vthe used acid, subjecting benzene to tl'ie action of the used acid to remove undesirable impurities, separating the purified benzene fA the acid,

alkylated aromatic hydrocarbons which comprises reacting an isoparain with a secondary olefin in the presence of an inorganic acid alkylation catalyst, separating the resulting alkylation products from the used acid, subjecting a hydrocarbon mixture containing secondary yand tertiary olens to contact with at least a part'of the used acid to separate the tertiary olen therefrom, alkylating an aromatic hydrocarbon with the thus separated olen in the presence of used acid :fromv in the presence of concentrated sulfuric acid,

contacting the latter with a hydrocarbon mixture containing isobutylene and a normal butyleue to separate at least a part of the isobutylene content from said normal butylene, alkylating the puried benzene with the thus separated isobutylene in the presence of a catalyst comprising used sulfuric acid from the isobutane alkylation, and feeding said separated normal butylene to the isobutane alkylation. v

2. A process for producing motor iuel components of high anti-knock value which comprises reacting isobutane with -a normai butylene in the presence of concentrated sulfuric acid, sepmating the resulting alkylation products from the used acid, subjecting a hydrocarbon ymixture containing isobutylene and a normal butyiene to contact with at least a part of the used acid to separate isobutylene therefrom, alkyiating benzene with the separated isobutylene in the presence of used sulfuric acid from the isobutane amlation, and feeding remaining normal butylene to said isobutane lation.

3. A process for producing isoparalns and alkylated aromatic hydrocarbons which comprises reacting an isoparamn with a secondary olefin in the presence of concentrated sulfuric acid, separating the resulting alkylation products from the used acid, subjecting a hydrocarbon mixture containing secondary and tertiary oleflns to contact with at least a part of the used acid to separatethe tertiary olen therefrom, alkylating an aromatic hydrocarbonwith the thus separated olefin in the presence of used sulfuric acid from the isoparamn alkylation, and feeding remainihe secondary olefin to said isoparaiiln alkyla- 4. A process for producing isoparafllns and separating the resulting almlation products from the used acid, subjecting an aromatic-hydrocarbon to the actionof the used acid to remove undesirable impurities, separating the puried aromatic hydrocarbon from the acid, contacting a hydrocarbon mixture containing secondary and tertiary olens with used acid from the isoparamn alkylation to separate the tertiary olenn therefrom, alkylating the purified aromatic hydrocarbon with the thus separated olefin in the presence of used sulfuric acid from the isoparamn alkylation, and feeding remaining secondary olefin to said isoparaiiiin alkylation.

6. A process for producing isoparzii' f.. alkylated aromatic hydrocarbons which comprises reacting an isopar with a secondary olen in the presence of concentrated sulfuric acid, separating the resulting alkylation products from the used acid, subjecting an aromatic hydrocarbon 'to the action of the used acid to remove undesirable impurities, separating the p i: :t e matic hydrocarbon from the acid, contacting the latter with a hydrocarbon mixture contai secondary and tertiary olefins to separate the ter tiary olen therem, alkylating the purined aromatic hydro amat with the thus separated olenn in the presence of used sulfuric yacid from the isoparamn alkylation, and feeding remaining tertiary olefin therefrom, alkylating the purified aromatic hydrocarbon with the thus separated olen in the presence of used acid from the iso paraihn alkylation, and feeding remaining secondary olen to said isoparaiiln alkylation.

' JOHN ANDERSON.

ROBERT C. CABTNER.

and 

